The present invention relates to a rotor blade trim tab, and more particularly to a self locking trim tab.
A rotary wing aircraft typically utilizes multiple rotor blades mounted to a rotor hub. A trim tab extends from the trailing edge of the rotor blade. The trim tab can be bent along its length about a spanwise axis to change the effective airfoil shape and thus change the lift, drag, and pitching-moment coefficients of the rotor blade airfoil at the local spanwise position of the tab. The ability to adjust these local airfoil parameters increases the amount of adjustment available to control global blade characteristics such as pitching moment slope, track, flutter stability, vibrations, and bending mode shapes.
Conventional trim tabs are readily adjustable in a field environment through a hand-held tool. Sections of the tab are manually bent by the operator applying force to the extending handle to set a portion of the trim tab. Each successive trim tab portion so bent is separately measured to determine the degree of bending. Other more sophisticated tools may also be utilized. Although effective, trim tab adjustment may be relatively time consuming even with the appropriate tools.
Trim tabs must hold a set to maintain an adjusted position relative to the rotor blade, provide an acceptable aerodynamic surface, and survive the high-strain environment found at the trailing edge of a rotor blade.
Accordingly, it is desirable to provide a rotor blade trim tab that is readily set without tools yet will maintain the adjusted position relative to the rotor blade.